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A B S T R A C TIn biomedical applications, silver nanoparticles (Ag NPs) are of great interest due to their cost-effective and environmentally friendly properties. Green synthesis of nanoparticles for biological research is a preferred choice since it does not require additional reducing agent. For this purpose, in this study, we aimed to synthesize the biogenic silver nanoparticles with the help of Rosa canina plant (Rc-Ag NPs) and then they have been tried for their antioxidant and antibacterial properties. UV-Vis spectrophotometer, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses were performed for characterization of Rc-Ag NPs. Antioxidant properties of silver nanoparticles synthesized with Rosa canina plant were investigated against 2,2 0 -diphenyl-1-picrylhydrazyl radical (DPPH). DNA dissociation activity of synthesized Rc-Ag NPs was studied, and DNA dissociation activity was shown. The antimicrobial activity of Rc-Ag NPs was also tested using micro-dilution. According to the results, Rc-Ag NPs synthesized were found to be highly effective for anti-oxidant, antibacterial, antifungal, and DNA cleavage activities.

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The ultimate aim of this study is to produce a composite of bimetallic platinum-cobalt nanoparticles and reduced graphene oxide (Pt-Co@rGO) based biosensor for the detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Those are biologically important molecules with the key functions for the human body. Pt-Co@rGO was synthesized using a microwave-assisted technique and utilized for the production of a highly sensitive and stable electrochemical biosensor. Detailed spectral XPS and Raman analysis, XRD, and TEM/HR-TEM characterization were also studied. Due to the superior activity and excellent conductivity of rGO, well-separated oxidation peaks of these biomolecules is proven by DPV (differential pulse voltammetry) and CV (cyclic voltammetry) measurements. The prepared Pt-Co@rGO-based biosensor showed high electrochemical activity, a broad linear response, high sensitivity, and acceptable limit of detection values for individual and simultaneous determination of AA, DA, and UA, under optimized conditions. The linear range of Pt-Co@rGO was found to be 170–200; 35–1500 and 5–800 µM for AA, DA, and UA, respectively. Moreover, the detection limit of the prepared composite was calculated as 0.345; 0.051; 0.172 µM for AA, DA, and UA, respectively. In the field of electrochemical biosensors, Pt-Co@rGO based sensor is highly promising due to its superior sensitivity and good selectivity properties.

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Today, the development of green nanocatalysts is among the popular topics due to the need for energy production and the cleaning of organic pollutants. In this approach, Bacillus thuringiensis, a bacterium, was used as a biosupport of ruthenium/nickel co-doped zinc nanoparticles (btRNZn NPs) to release hydrogen from the methanolysis of sodium borohydride (NaBH 4 ). In addition, their photocatalytic activity was reported against Methyl Orange (MO) organic dye. This study focused on the preparation, characterization, and catalytic and photocatalytic activity of the btRNZn biocatalyst for the release of hydrogen from the methanolysis of NaBH 4 and removal of MO dye. According to TEM analysis, the average size of btRNZn NPs was found to be 11.78 nm; in addition, btRNZn NPs showed a photodegradation effect of 68.2% against MO dye at 90 min, and its photocatalytic mechanism was discussed. The effects of the catalyst, substrate, and temperature in the methanolysis reaction of NaBH 4 in the presence of the catalyst were investigated extensively. The reaction kinetics was calculated, and TOF, activation energy, and enthalpy energy were measured as 2497.14 h −1 , 14.89 kJ/mol, and 12.35 kJ/mol, respectively. It was observed that the methanolysis process is a first-order reaction based on the amount of the catalyst and substrate. This study aimed to synthesize a nanobiocatalyst (btRNZn NPs) by a biological method, and it will be used as a great photocatalyst to prevent wastewater pollution; also, it can be an excellent catalyst to produce hydrogen from NaBH 4 methanolysis. The application of btRNZn NPs in solar photocatalysis to prevent wastewater pollution and to research it for energy production through hydrogen creation are both made clear by these studies.

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